Transcript
BKF 3843 & PROCESS CONTROL
INSTRUMENTATION
:By Junaidi Bin
Zakaria, FKKSA UMP
JUNAIDI BIN ZAKARIA A3-2-9
013-9683471/09-5492914 junaidibz@ump.edu.my
ASSESSMENT METHOD
TEST 1 20%TEST 2 20%QUIZZES 10%ASSIGNMENTS 10%FINAL EXAM 40%
TOTAL 100%
CHAPTER REVIEW
CHAPTER 1
Introduction to Process Control
:By Junaidi Bin
Zakaria, FKKSA UMP
TaskIn your own words, - what is process control &
instrumentation - explain the importance of process
control
Learning ObjectivesDescribe the importance process controlDefine and identify controlled, manipulated
variables and disturbance for a given process
Explain the implementation of process control in industries
Explain feedback and feedforward control
When I run a kinetics experiment, how do I maintain the temperature and level at desired values?
How do I manufacture products with consistently high quality when raw material properties change?
How much time do I have to respond to a dangerous situation?
Why do I learn Process Control and Instrumentation Course
Why Is Control Necessary?
Control SystemProcess control principle
How to keep the level at
desired value, H?
h
Qin
Qout
H
Control SystemProcess control principle
Human Aided ControlThe equipment has
the local gauge/ side tube
Controlled variable-liquid level
Manipulated variable-valve
What will cause the level high/ low?
Qin
h
Qout
H
Control SystemProcess control principle
Automatic controlMachine, electronic, or
computer replace human operation
h
Qout
Controller
Actuator
Sensors
u
Qin
Categories of control systems1. Servomechanisms – change an output
variable2. Regulators – hold an output variable
Most chemical process are regulators, eg. Feedback and Feedforward
16
What is control? Control
To maintain desired conditions in a physical system by adjusting selected .variables in the system
Control System
The control systems appear to have three basic elements which is
FINALELEMENTCONTROLLERSENSOR
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SENSOR
- The first task that of acquiring information about the process output.variables
- Sensors are usually needed for pressure , , temperature , liquid level flow
.and composition measurement-thermocouple: temperature measurement- differential pressure cell: for liquid level measurements- / gas liquid chromatographs: composition measurements
CONTROLLER
- , ‘ ’ The decision maker and hence the heart of the control system
FINALELEMENT
- , , , Pump variable speed fans compressor conveyors
Transmitter : How process information acquired by the sensor get back to , the controller and the controller decision gets back to the process
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Process
Controller
OUTPUT
sensorFinal control element
INFORMATION
Transmitter
Transmitter
INPUT
Decision
DISTURBANCE
The feedback control configuration
Control Terminology
Controlled variables - these are the variables which quantify the performance or quality of the final product, which are also called output variables.
Manipulated variables - these input variables are adjusted dynamically to keep the controlled variables at their set-points.
Disturbance variables - these are also called "load" variables and represent input variables that can cause the controlled variables to deviate from their respective set points.
Ch
ap
ter
1
Task 1You are implementing control manually
Task 2State your own objective for this chemical
reactor.List the controlled, manipulated variables
and disturbance(s)
Answer for Task 2Level and Temperature Control
LC
TC
Answer for Task 2Composition Control
AC
JIGSAW
Classification of process control strategies
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General Form of Control System Configuration
Structure of Open-loop System (struktur bg sistem gelung terbuka)
PROCESS
Disturbances variable
Manipulated variableControlled variable
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FEEDBACK
Uses direct measurements of the controlled variables to adjust the values of the manipulated variables.
FEEDFORWARD
Uses direct measurements of the disturbances variables to adjust the values of the manipulated variables.
Method 1
Method 2
35
Process
Disturbances variable
Manipulatedvariable Controlled
variable
controller
Process
Disturbances variable
Manipulatedvariable
Controlledvariable
controller
§It does not required identification and measurement of any disturbance.§It is not sensitive to modeling errors.§It is not sensitive to parameter changes.
Advantages
Disadvantages
§Acts before the effects of a disturbances has been felt by the system§Is good for slow systems or with significant dead time§It does not introduce instability in the closed-loop response
§It wait until the effect of the disturbances has been felt by the system§It is unsatisfactory for slow processes§It may create instability in the close-loop response
§Required identification & measurement of disturbances§Cannot cope with unmeasured disturbance§Sensitive to process parameter variations§Requires good knowledge of the process control
Feed Back Feed Forward
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Instrumentation Symbols
Symbols of instruments used in :process controls drawings
A : AnalyzerF : Flow rateL : Level of liquid or solids in a vesselP : PressureT : TemperatureC : ControllerV : Valve
1. Measurement and Actuation
2. Safety, Environment and Equipment
Protection
3a. Regulatory Control
4. Real-Time Optimization
5. Planning and Scheduling
Process
3b. Multivariable and Constraint
Control
(days-months )
(< 1 Second )
(< 1 second )
( seconds-minutes )
( minutes-hours )
( hours-days )
Case Study
Case 1: High pressure is dangerous. Case 2: No flow could damage the pumpCase 3: High temperature may cause
thermal loading in the columnCase 4: Quality of product at the bottom
column is the most criticalCase 5: Keep the process at smooth rate,
avoid dry column
Case 1
Case 2
Case 3
High thermal loading
TC
Case 4Adjusting the heating and flowrate
Case 5
THANK YOU
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